A storage device having a cluster configuration, in which a plurality of storage nodes are assembled, operates each storage node in parallel to thereby be able to realize high data access performance by parallel access and realize high availability due to data redundancy. For example, Patent Document 1 discloses configuring a large-scale storage device by interconnecting a plurality of storage nodes through a network. In the following description and drawings, an internal network of the storage device in which a plurality of storage nodes is connected is referred to as a storage internal network. The storage node is sometimes simply referred to as a node.
The storage node generally has a storage controller and a randomly accessible nonvolatile recording medium. The recording medium is a disk array having a large number of hard disk drives and nonvolatile semiconductor memory drives, for example. The storage controller has a front end interface for connecting a host device (host system or the like), a back end interface for connecting a disk array, and a cache memory temporarily storing user data which the host device reads from and writes in the disk array. The storage controller further has a control memory storing control data to be handled in the storage controller and a processor for controlling the data transfer of the user data and the control data. In the storage device in which a plurality of storage nodes is connected, the plurality of storage nodes sends and receives the user data and the control data between the nodes through the storage internal network.
As the standard of a network suitable for connection between computer nodes including the storage node, “InfiniBand” of Non-Patent Document 1 is known. Moreover, an improved technique relating to the InfiniBand of Patent Document 2 is known.